In photographic and X-ray examination of subjects it is often advantageous to produce a three-dimensional image of the subject which can then be electronically viewed from various selected angles to reconstruct one or more desired new two-dimensional views of the subject other than the immediate views dictated by the exposure apparatus. This has been possible with well known computer assisted tomography and magnetic resonance imaging systems which expose multiple two-dimensional video images, and then extract the video information from many two-dimensional images by computer processing. Computer assisted tomography requires several minutes to acquire the many exposures around the subject's heart, too long a time to obtain sharp images of the pulsing heart and blood vessels. Magnetic resonance imaging lacks the resolution of X-radiology, or obtains resolution at the expense of long exposure periods. Other systems employing fast rotating X-ray tubes are very slow because they require that the exposures be gated by cardiographic pulses; and their cost is prohibitive for routine clinical use. Other methods involving reconstruction of views around a common rotation axis are impractical because of the computational complexity and time.
It is the object of the present invention to provide a method and apparatus for producing three-dimensional video signals of a three-dimensional subject, such as tree-like group of branched blood vessels, from which signals a desired two-dimensional view at any selected view angle may be reconstructed in real time (in seconds), with resolution as clear as conventional direct exposures, and using uncomplicated, stationary X-ray tube exposures. A further object is to exclude artifacts from such reconstructions.